Method and apparatus for manufacturing a solar energy collector

ABSTRACT

Illustratively, a portion of a thin sheet of high thermal conductivity material is wrapped in tight thermal communication about the external surface of a working fluid conduit. A hinged male die presses part of the portion of the sheet into a semi-cylindrical female mold. The die is removed and the fluid conduit is placed in the semi-cylindrical sheet. Another hinged mold, with the aid of a drawing up mechanism bend the balance of the sheet portion into thermal communication with the hitherto exposed conduit surface. Beveled mold edge also exposes a seam for joining the sheet portion to the balance of the sheet.

TECHNICAL FIELD

This invention relates to methods and apparatus for making solar energycollection equipment and, more particularly, to methods and apparatusfor wrapping a portion of a sheet of thermally conductive material aboutthe outer surface of a fluid conduit, and the like.

BACKGROUND ART

Unquestionably, there is a need to provide efficient means for applyingsolar energy to an increasing number of human and industrial uses, asother energy sources are depleted or become prohibitively expensive. Theapplication of solar energy to building heating and cooling requirementsare typical of this need. Among other things, an effective solar energysystem for use in buildings must be not only relatively inexpensive, butalso reliable and maintainence-free for long periods of time.Considering solar energy system costs, moreover, an apparently smallimprovement in thermal efficiency for one system with respect to otherswill, over the anticipated life of the slightly more efficient system,give that product a marked technical and commercial advantage.

Through the years, a number of proposals for collecting solar heat andutilizing this heat to increase water temperature for household heatingand similar purposes have been advanced. Representative of many of theseproposals are the following U.S. patents:

U.S. Pat. No. 4,029,080 relies on translucent roof panels and convectiveair flow between the roof rafters to convey heat to a fluid-filled tube.

U.S. Pat. No. 4,003,365 shows a system for wetting a solar-exposedmembrane in order to heat the wetting water. The water, warmed in thismanner, is stored in a reservoir for subsequent use.

U.S. Pat. No. 3,893,508 relates to pre-stressed concrete walls thatcontain cooling and heating systems.

U.S. Pat. No. 3,207,211 describes heat absorbing tabs that are securedto an eaves trough for melting ice and slush in order to promote waterdischarge from the trough.

U.S. Pat. No. 1,473,018 discloses a heat absorbing plate and a number ofpassageways associated with the plate to enable fluid in thesepassageways to absorb heat from the plate.

U.S. Pat. No. 705,350 describes a pair of closely spaced plates thatform a capillary tube in which the water that is to be heated is spreadas a thin film.

In all of the patents summarized above, however, none suggest arelatively inexpensive method for making a tube in which heat isconducted with high thermal efficiency to the fluid within with sturdy,inexpensive apparatus that can be transported with ease from oneconstruction site to another.

SUMMARY OF THE INVENTION

These foregoing and other disadvantages of prior art solar heatingsystem are overcome, to a great extent, through the practice of theinvention.

One of the more efficient solar energy collecting systems is describedin detail in my U.S. patent application Ser. No. 896,470, filed Apr. 14,1978, titled "Solar Energy Collector and Associated Methods Adapted ForUse With Overlapped Roof Shingles On The Roof Of A building". In thatpatent application, I show a thin flexible metal plate interposedbetween the overlapped shingles to enable heat that is absorbed by theshingles to be transferred to the metal plate. These plates, in turn,each have portions that are wrapped around individual fluid-containingtubes to permit the absorbed heat to be conveyed through the respectivetube and to the water or other working fluid within.

Naturally, extremely close contact should be established at theinterface between the tube and the portion of the plate with which it isenclosed. A loose fit, air gaps, and the like at this interface candegrade the thermal efficiency of the entire system. The method ofmanufacturing this structural combination, moreover, should beinexpensive and swift, with the further capability of being suitable forswift transportation from one construction site to another.

Thus, in accordance with the invention, a crescent-like make die ishinged to press a thin sheet of high thermal conductivity material intoa half-cylindrical female mold. Upon removing the male die, a tube isplaced on top of the bent portion of the sheet within the mold.Subsequently, another female mold of half cylindrical shape is hinged tothe first mold and bends the remaining portion of the sheet over thebalance of the exposed surface of the tube.

The outer surfaces of the female molds are provided with a drawing upmechanism that presses the edge of the sheet tightly to the body of thematerial in the area in which the sheet enters the molds in order toestablish an interface between the tube and the sheet that is of highthermal efficiency. Further, the edge of at least one of the molds isbeveled to expose a seam for soldering, brazing or otherwise suitablyjoining the edge of the bent portion to the body of the sheet.

The female molds are removed and the finished combination of sheet andtube is ready for installation. Thus, there is provided a sturdy andrelatively inexpensive apparatus for producing sheet and tubecombinations of high thermal conductivity in a swift and efficientmanner.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows in side elevation an initial arrangement for producing atube and sheet combination in accordance with principles of theinvention;

FIG. 2 shows the initial arrangement of FIG. 1 after it has beenoperated;

FIG. 3 shows a further structural arrangement for producing the tube andsheet combinations; and

FIG. 4 shows the arrangement of FIG. 3 after it has been operated.

DETAILED DESCRIPTION

As shown in FIG. 1, a thick plate 10 of aluminum or the like issupported on a solid foundation 11. A typical plate 10 would be 28inches long, 3 inches wide and 1/4 inch thick. Extending along alengthwise edge of the plate 10 is a half cylindrical mold 12. As shown,the longitudinal axis of the mold 12 is parallel to the long edge of theplate 10. A mold, suitable for the intended use could be 24 inches long.The inside radius of the mold 12 should be equal to the outside radiusof the tube plus half the gauge of the sheet, the tube and sheet beingdescribed subsequently in more complete detail.

A hinge 13 is formed on a part of the plate 10 that is adjacent to themold 12. The hinge 13, moreover, protrudes above the surface of theplate 10. The hinge 13 provides a pivotal axis for a crescent-like maledie 14 that extends with its curved or rounded die surface above themold 12.

As shown in FIG. 1, a die handle 15 extends from the male die 14 throughthe hinge 13 to extend across the plate 10. A removable pivot pin 16extends through the usual aperture in the hinge 13 and a bore (notshown) in the die handle 15 to complete the pivotal axis for the maledie 14. An illustrative male die 14 would be a 24 inch long, 1/4 inchthick metal plate to which the crescent like shape is attached. Furtherin this respect, the width of the male die 14 is slightly less than halfof the depth of the female mold 12.

A sheet 17 of copper or some similar material that is characterized by ahigh thermal conductivity is placed on the plate 10 and temporarilysecured to that plate by means of clamps or the like (not shown in thedrawing).

The sheet 17 has a portion 20 that not only extends all of the wayacross the open side of the female mold 12, but also protrudes for somedistance beyond.

As shown in FIG. 3, another female mold 21 is connected to the edge ofthe mold 12 that is spaced from the plate 10 by means of a further hinge22. The mold 21 also has a handle 23 that is secured to its outersurface. The handle 23 is spaced away from beveled edge 24 of the mold21. A hinge pin 25 completes the union between the meshed edges of thefemale molds 12 and 21. Preferably, the female mold 21 is attached tothe outside edge of a 24 inch long heavy duty hinge 22. The insidedimensions of the female mold 21 should approximate those of the cavityin the mold 12, with the exception of a 1/16 of an inch gap at thebeveled edge 24.

A drawing up device 26 is secured to the outer surface of the femalemold 21. Illustratively, the device can be in the form of a number ofaligned bosses to permit clamps or other fixtures to engage the device26 and the plate 10 in order to squeeze the female molds 12, 21 togetheras described subsequently in further detail.

In operation, as best shown in FIG. 2 the male die handle 15 is pivotedin the direction of the arrow 27 in order to press part of the sheetportion 20 into the half cylindrical female mold 12. As shown, part ofthe sheet portion 20 takes the shape of the mold surface. The bitter endof the portion 20, however, stands upright in a direction that isgenerally perpendicular to the plate 20.

The hinge pin 16 for the male die 14 is removed in order to permit thedie to be taken away prior to the next step in the process. Uponremoving the male die 14 a length of tube 30 (FIG. 3) is placed on thenow partially formed sheet portion 20. The female mold handle 23 (FIG.4) is drawn in the direction of arrow 31, a direction that is oppositeto the motion of the male die 14 (FIG. 2).

Although good, uniform, and thermally efficient contact is establishedthrough this manipulation of the female mold handle 23, a superiorcontact is established by operating the drawing up device 26 to veryclosely stretch and press the sheet portion 20 against the outer surfaceof the tube 30.

To complete this phase of the assembly, solder, braze or other suitablebonding material is applied through the beveled edge 24 to join the edgeof the portion 20 to the body of the sheet 17.

Thus, there is provided in accordance with the invention a sturdy,portable and relatively inexpensive apparatus and method for producingthermally efficient tubing with an attached solar heat collectingsurface.

I claim:
 1. A method for producing thermally efficient tubing with an attached solar heat collecting sheet; the method comprising steps of:clamping a portion of the sheet above a half-cylindrical female mold, pivoting a male die against the sheet to force the sheet to conform to the half-cylindrical shape of the female mold and to enable the bitter end of said sheet to stand generally perpendicular to the clamped portion of the sheet, removing the male die from the female mold and sheet combination, placing a tube in the female mold on top of the conforming shape of the sheet portion, drawing another female mold over the exposed surface of the tube to press the balance of the sheet portion against the tube and to cause this sheet portion to conform to the shape of the tube, drawing the female molds together to stretch and to press the sheet portion into close contact with the tube, and joining the bitter end of the sheet portion to the body of the sheet. 